[PATCH v4 2/2] thermal: add interface to support tune governor in run-time

[Wei Ni <wni@nvidia.com>]

In the of-thermal driver, it register a thermal zone device
without governor, since the governers are not static, we
should be able to update to a new one in run-time, so I add
a new fucntion thermal_update_governor() to do it.

Change-Id: Ie4995d6404d6d4f16250958487f3e3b8f63fc4c6
Signed-off-by: Wei Ni <wni@nvidia.com>
---
 Documentation/thermal/sysfs-api.txt |    4 ++++
 drivers/thermal/thermal_core.c      |   38 ++++++++++++++++++++++++++++-------
 include/linux/thermal.h             |    1 +
 3 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
index 8459d45..bcd50b5 100644
--- a/Documentation/thermal/sysfs-api.txt
+++ b/Documentation/thermal/sysfs-api.txt
@@ -405,3 +405,7 @@ platform data is provided, this uses the step_wise throttling policy.
 This function serves as an arbitrator to set the state of a cooling
 device. It sets the cooling device to the deepest cooling state if
 possible.
+
+5.5:thermal_update_governor:
+This function update the thermal zone's governor to a new one.
+Returns 0 if success, an erro code otherwise.
diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index a91684b..ef0fc40 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -130,6 +130,35 @@ exit:
 	return;
 }
 
+/**
+ * thermal_update_governor() - update the thermal zone device's governor
+ * to a new one.
+ * @tzd: pointer of thermal zone device, which need to update governor.
+ * @name: new governor name.
+ *
+ * Return: On success returns 0, an error code otherwise
+ */
+int thermal_update_governor(struct thermal_zone_device *tzd,
+			    const char *name)
+{
+	struct thermal_governor *new_gov;
+	int ret = 0;
+
+	mutex_lock(&thermal_governor_lock);
+
+	new_gov = __find_governor(name);
+	if (!new_gov) {
+		ret = -EINVAL;
+		goto exit;
+	}
+
+	tzd->governor = new_gov;
+
+exit:
+	mutex_unlock(&thermal_governor_lock);
+	return ret;
+}
+
 static int get_idr(struct idr *idr, struct mutex *lock, int *id)
 {
 	int ret;
@@ -734,22 +763,17 @@ policy_store(struct device *dev, struct device_attribute *attr,
 {
 	int ret = -EINVAL;
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	struct thermal_governor *gov;
 	char name[THERMAL_NAME_LENGTH];
 
 	snprintf(name, sizeof(name), "%s", buf);
 
-	mutex_lock(&thermal_governor_lock);
-
-	gov = __find_governor(strim(name));
-	if (!gov)
+	ret = thermal_update_governor(tz, strim(name));
+	if (ret < 0)
 		goto exit;
 
-	tz->governor = gov;
 	ret = count;
 
 exit:
-	mutex_unlock(&thermal_governor_lock);
 	return ret;
 }
 
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index f7e11c7..715b3cd 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -293,6 +293,7 @@ struct thermal_instance *get_thermal_instance(struct thermal_zone_device *,
 		struct thermal_cooling_device *, int);
 void thermal_cdev_update(struct thermal_cooling_device *);
 void thermal_notify_framework(struct thermal_zone_device *, int);
+int thermal_update_governor(struct thermal_zone_device *, const char *);
 
 #ifdef CONFIG_NET
 extern int thermal_generate_netlink_event(struct thermal_zone_device *tz,
-- 
1.7.9.5